A known seat slide apparatus (seat track apparatus) for a vehicle is disclosed in JP2006-298104A (hereinafter, referred to as Reference 1, see FIGS. 7 and 8). The seat slide apparatus arranged at each of both sides at a lower portion of a seat of the vehicle in a width direction of the seat includes a lower rail fixed to a floor of the vehicle and an upper rail fixed to a seat and supported by the lower rail so as to be relatively movable thereto. Stoppers having plate shapes are formed at an intermediate portion in a longitudinal direction of the lower rail. In particular, portions of a bottom wall of the lower rail is cut by a predetermined angle relative to the bottom wall so as to protrude obliquely upward from both sides in a width direction of the lower rail, thereby forming the stoppers. Meanwhile, front stoppers are cut obliquely downward from respective front ends of vertical walls of the upper rail, which are arranged in a width direction of the upper rail. Further, rear stoppers are cut obliquely downward from respective rear ends of the vertical walls of the upper rail. The stoppers and the front and rear stoppers are arranged in the longitudinal direction so that respective front facing surfaces of the stoppers partially face respective rear facing surfaces of the front stoppers in a moving direction of the upper rail and so that respective rear facing surfaces of the stoppers partially face respective front facing surfaces of the rear stoppers in the moving direction of the upper rail. The rear stoppers engage with the stoppers in accordance with a forward movement of the upper rail while the front stoppers engage with the stoppers in accordance with a rearward movement of the upper rail, thereby restricting a movable range (slide stroke) of the upper rail relative to the lower rail.
According to the seat slide apparatus described in Reference 1, the slide stroke of the upper rail relative to the lower rail is restricted by the direct engagement (contact) between the stopper formed or fixed at the lower rail and the front and rear stoppers formed or fixed at the upper rail; therefore, the arrangement of the first stopper and front and rear second stoppers limits the movable range. In other words, a position in which the stopper is cut from the bottom wall of the lower rail so as to protrude therefrom obliquely upward and positions in which the front and rear stoppers are cut from the vertical wall so as to protrude therefrom obliquely downward need to be changed in order to modify the slide stroke. Further, the upper and lower rails need to be cut in accordance with a desired slide stroke. As a result, the feasibility of layout design of the movable range between the upper and lower rails may be limited.
A need thus exists for a seat slide apparatus for a vehicle, which is not susceptible to the drawback mentioned above.